1. Field of the Invention
This invention relates generally to electrochemical cells and more particularly to the measurement of characteristics, such as solution conductivity and spatial current distribution, of operating electrochemical cells.
2. Description of the Prior Art
Solution conductivity measurements in electrochemical cells are typically made by ac bridge techniques because of the problems involved in overcoming electrode polarization when dc techniques are used. Although dc techniques have been developed that overcome these problems, most require a constant open circuit potential and non-polarizable reference type electrodes which raise possibilities of incompatibility with or contamination of the cell solution. Avoidance of electrode polarization by using a small current results in an IR drop that is too small to be easily measured without cumbersome apparatus that is not well adapted to routine use.
Measurement of spatial current distribution in operating electrochemical cells depends upon the measurement of the voltage between two electrodes. However, the measured voltage depends upon the alignment of the electrodes with respect to the current direction and can vary from a maximum value when the line connecting the probes is parallel to the current direction to zero when the line between the probes is perpendicular to the current direction. Some uncertainty is thus introduced into the measured voltage which makes rapid and precise measurements difficult.